Home > Press > Using single quantum dots to probe nanowires: Lighting up plasmonic wires with nanometer accuracy
 |
(a) This is an optical image of the microfluidic crossed-channel device. Flow in the center control region (dashed circle) is manipulated in two dimensions by 4 external electrodes (not shown). Scale bar is 500 μm. (b) This is a schematic of the positioning and imaging technique. A single QD is driven along a trajectory close to the wire by flow control. The inset shows a microcope image of a typical nanowire with 1 μm scale bar.
Credit: JQI |
Abstract:
Modern telecommunications happens because of fast electrons and fast photons. Can it get better? Can Moore's law---the doubling of computing power ever 18 months or so---be sustained? Can the compactness (nm-scale components) of electronics be combined with the speed of photonics? Well, one such hybrid approach is being explored at the Joint Quantum Institute (*), where scientists bring together three marvelous physics research fields: microfluidics, quantum dots, and plasmonics to probe and study optical nanostructures with spatial accuracy as fine as 12 nm.
Using single quantum dots to probe nanowires: Lighting up plasmonic wires with nanometer accuracy
College Park, MD | Posted on February 5th, 2013
PLASMONICS
When light strikes a strip of metal an electron wave can be excited in the surface. Is this "surface plasmon" a bit of light or electricity. Well, it's a bit of both. The wavelength of this electromagnetic wave is shorter and the energy density higher than that of the incoming laser light; the plasmon is thus tightly localized light constrained to propagate along the meal surface. The science of "plasmonics" has arisen to capitalize on various imaging, sensing, and processing abilities inherent in plasmons. To start with, though, one needs to know exactly what happens at that laser-excited metallic surface. That light is converted into the plasmonic wave; later the energy can be reconverted into light.
Here's where the JQI experiment comes in. The main result of the work, published February 5 in the journal Nature Communications, is to provide a map showing how the metal strip, in this case a silver wire 4 microns long and 100 nm wide, lights up.
MICROFLUIDICS AND QUANTUM DOTS
The other two chief components of the experiment, in addition to plasmonics, are microfluidics and quantum dots. Microfluidics, a relatively new science all by itself, features the movement of nanoliter volumes of fluids through channels defined on microchips, analogous to the conducting paths strung across microprocessors for carrying electrical currents. Quantum dots, nanometer-sized semiconductor balls, are tailored to possess a specified set of allowed energy states; in effect the dots are artificial atoms that can be moved around. In the JQI experiment the 10-nm-wide dots (the important cadmium-selenide layer is only 3 nm thick) float in a fluid whose flow can be controlled by varying an applied voltage. The dots are drawn up close to the nanowire as if they were mines next to a submarine.
Indeed the dot is there precisely to excite the wire. The dot is fluorescence machine---in a loose sense a nanoscopic lightbulb. Striking it with green laser light, it quickly re-emits red light (one photon at a time), and it is this radiation which excites waves in the nearby wire, which acts like an antenna. But the interaction is a two-way street; the dot's emissions will vary depending on where along the length of the wire it is; the end of the wire (like any pointy lightning rod on a barn) is where electrical fields are highest and this attracts the most emission from the dot.
A CCD camera captures light coming from the dots and from the wire. The camera qualities, the optical properties of the dot, the careful positioning of the dot, and the shape and purity of the nanowire combine to provide an image of the electric field intensity of the nanowire with 12-nm accuracy. The intensity map shows that the input red light from the quantum dot (wavelength of 620 nm) has effectively been transformed into a plasmonic wavelength of 320 nm.
Chad Ropp is a graduate student working on the project and the lead author on the paper. "Plasmonic maps have been resolved before, but the quantum mechanical interactions with a single emitter have not, and not with this degree of accuracy," said Ropp.
POSSIBLE APPLICATIONS
In an actual device, the quantum dot could be replaced by a bio-particle which could be identified through the nanowire's observed effect on particle's emissions. Or the dot-wire duo could be combined in various configurations as plasmonic equivalents of electronic circuit components. Other uses for this kind of nanowire setup might exploit the high energy density in the plasmonic state to support nonlinear effects. This could enable the nanowire-dot combination to operate as an optical transistor.
"Nanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot," Chad Ropp, Zachary Cummins, Sanghee Nah, John T. Fourkas, Benjamin Shapiro, Edo Waks, Nature Communications, paper published online 5 February 2013. Chad Ropp, , 301-405-5010
####
About Joint Quantum Institute
The Joint Quantum Institute is operated jointly by the National Institute of Standards and Technology in Gaithersburg, MD and the University of Maryland in College Park.
For more information, please click here
Contacts:
Phillip F. Schewe
301-405-0989
Copyright © Joint Quantum Institute
If you have a comment, please
Contact us.
Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Bookmark:
News and information
Pioneering breakthrough of chemical nanoengineering to design drugs controlled by light June 18th, 2013
Study Shows How the Nanog Protein Promotes Growth of Head and Neck Cancer June 18th, 2013
New Method to Synthesize Zinc Oxide Nanoparticles with High Catalytic Activity June 18th, 2013
Production of Polyaniline Biosensors Modified with Conductive Polymer Composites June 18th, 2013
Laboratories
Efficient and inexpensive: Researchers develop catalyst material for fuel cells: Platinum-nickel nano-octahedra save 90 percent platinum June 17th, 2013
Discovery of new material state counterintuitive to laws of physics June 14th, 2013
New quantum dot technique combines best of optical and electron microscopy June 12th, 2013
Exposure to Air Transforms Gold Alloys Into Catalytic Nanostructures: Brookhaven Lab scientists create promising gold-indium oxide nanoparticles through room-temperature oxidation June 12th, 2013
Microfluidics/Nanofluidics
Whispering light hears liquids talk: University of Illinois researchers build first-ever bridge between optomechanics and microfluidics June 7th, 2013
New microfluidic method expands toolbox for nanoparticle manipulation June 5th, 2013
Portable device provides rapid, accurate diagnosis of tuberculosis, other bacterial infections May 6th, 2013
Scientists image nanoparticles in action April 25th, 2013
Govt.-Legislation/Regulation/Funding/Policy
3-D printing could lead to tiny medical implants, electronics, robots, more June 18th, 2013
Working backward: Computer-aided design of zeolite templates: Rice scientists apply drug-design lessons to production of industrial minerals June 17th, 2013
An Innovative material for the Green Earth: Simple and inexpensive process to make a material for CO2 adsorption June 17th, 2013
Discovery of new material state counterintuitive to laws of physics June 14th, 2013
Chip Technology
Which qubit my dear? New method to distinguish between neighbouring quantum bits June 18th, 2013
SEMATECH to Address Critical Supply Chain Challenges and Present Latest Technology Advances at SEMICON West 2013 June 17th, 2013
Imec shows multiple enhancement options for next-generation FinFETs: Leading nano-electronics R&D center addresses key challenges of Germanium finFET technology at VLSI 2013 June 14th, 2013
Imec showcases innovation in RRAM R&D at VLSI Technology Symposium June 14th, 2013
Optical Computing
Rice unveils method for tailoring optical processors: Arranging nanoparticles in geometric patterns allows for control of light with light May 21st, 2013
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
UC Riverside scientists discovering new uses for tiny carbon nanotubes: Adding ionic liquid to nanotube films could build smaller gadgets, and create more cost effective 'Smart Windows' that darken in bright sun May 15th, 2013
Use of laser light yields versatile manipulation of a quantum bit May 1st, 2013
Discoveries
Which qubit my dear? New method to distinguish between neighbouring quantum bits June 18th, 2013
Pioneering breakthrough of chemical nanoengineering to design drugs controlled by light June 18th, 2013
Study Shows How the Nanog Protein Promotes Growth of Head and Neck Cancer June 18th, 2013
New Method to Synthesize Zinc Oxide Nanoparticles with High Catalytic Activity June 18th, 2013
Announcements
Pioneering breakthrough of chemical nanoengineering to design drugs controlled by light June 18th, 2013
Study Shows How the Nanog Protein Promotes Growth of Head and Neck Cancer June 18th, 2013
New Method to Synthesize Zinc Oxide Nanoparticles with High Catalytic Activity June 18th, 2013
Production of Polyaniline Biosensors Modified with Conductive Polymer Composites June 18th, 2013
Quantum Dots/Rods
New quantum dot technique combines best of optical and electron microscopy June 12th, 2013
CNSE Welcomes Record Number of Students, Majority of Whom are New Yorkers, for Prestigious Summer Internship Program June 12th, 2013
Perfectly doped quantum dots yield colors to dye for May 11th, 2013
Researchers use graphene quantum dots to detect humidity and pressure May 8th, 2013
Photonics/Optics/Lasers
Data Highways for Quantum Information June 13th, 2013
Polymer structures serve as 'nanoreactors' for nanocrystals with uniform sizes, shapes: Tiny chemistry June 11th, 2013
Catching individual molecules in a million with optical antennas inside nano-boxes June 10th, 2013
Whispering light hears liquids talk: University of Illinois researchers build first-ever bridge between optomechanics and microfluidics June 7th, 2013
Alliances/Partnerships/Distributorships
Imec presents 4K2K CMOS image sensor together with Panasonic: The co-developed imager sensor chip targets high speed, high resolution imaging applications such as next generation HDTV June 18th, 2013
European Technology Platform for Nanomedicine and Nanomed2020 European Consortium Launch the Nanomedicine Award June 17th, 2013
SEMATECH to Address Critical Supply Chain Challenges and Present Latest Technology Advances at SEMICON West 2013 June 17th, 2013
SEMATECH Names William R. Rozich Chairman of the Board June 13th, 2013
Research partnerships
3-D printing could lead to tiny medical implants, electronics, robots, more June 18th, 2013
Imec presents 4K2K CMOS image sensor together with Panasonic: The co-developed imager sensor chip targets high speed, high resolution imaging applications such as next generation HDTV June 18th, 2013
Pioneering breakthrough of chemical nanoengineering to design drugs controlled by light June 18th, 2013
Study Shows How the Nanog Protein Promotes Growth of Head and Neck Cancer June 18th, 2013